K-Stew came within feet of Liberty — the ex-wife of Rupert Sanders, with whom she cheated on Robert Pattinson — and it reportedly took a toll on her.

Kristen Stewartapparently can’t even enjoy an evening of music without being reminded of her past mistakes! Kristen and Robert Pattinsonattended Jurassic 5‘s Coachella concert April 12, when they suddenly realized they were standing near Liberty Ross! “The last thing she wanted to do was make Liberty feel uncomfortable,” a source tells The UK’s Sun. “She looked pretty upset in the backstage bar later on that evening.”

The source adds that Kristen “still feels incredibly guilty” about what happened — Kristen cheated on Rob with Snow White and the Huntsman director Rupert Sanders, who was married to Liberty at the time — so she thought it’d be best to avoid Liberty altogether.

Liberty was there with new-boyfriend Jimmy Iovine, as well as U2 rocker Bono, seemingly unaware that her ex-husband’s mistress was also in the audience.